An ultrasound diagnostic system has become an important and popular diagnostic tool since it has a wide range of applications. Specifically, due to its non-invasive and non-destructive nature, the ultrasound diagnostic system has been extensively used in the medical profession. Modern high-performance ultrasound diagnostic systems and techniques are commonly used to produce two or three-dimensional diagnostic images of internal features of an object (e.g., human organs).
A diagnostic ultrasound system generally uses an ultrasound probe containing an array of transducer elements, which may be formed by piezoelectric materials, to transmit and receive ultrasound signals. The ultrasound diagnostic system electrically excites transducer elements to generate ultrasound signals that travel into the body. Echoes reflected from tissues and organs return to the transducer elements and are converted into electrical signals. An ultrasound image is formed by processing the electrical signals outputted from the transducer elements. Thus, an acoustic property of the ultrasound probe is very important to form an accurate ultrasound image.
A hydrophone has been traditionally used to test the acoustic property of the ultrasound probe such as a beam profile, an acceptance angle and the like. In such a case, approximately 4 to 5 hours are required to test the beam profile and the acceptance angle for each of the transducer elements included in the ultrasound probe. Further, an extra device for automatically controlling a position of the hydrophone is required to accurately test the acoustic property of the ultrasound probe. Additionally, when a needle-type hydrophone is adopted to test the acoustic property of the ultrasound probe, the hydrophone may be inevitably positioned within a sound field, which may affect a free field condition. Thus, a distorted acoustic property may be obtained. Also, a response property of the hydrophone itself may cause the acoustic property to be distorted.
Recently, a method of using a Schlieren system has been utilized as a faster technique to test the acoustic property of the ultrasound probe. The Schlieren system is a system for visualizing an acoustic field of the ultrasound signals by using a characteristic of the light in which its refractive index varies according to density variation of the ultrasound signals in a transmission medium (e.g., water). This method of using the Schlieren system may perform the test faster than the hydrophone-based method. The Schlieren system is typically configured with a water tank for containing water as the transmission medium of the ultrasound signals, a plurality of lenses for collimating and focusing the light and the like. Thus, when the water tank or the lenses are contaminated, the Schlieren system may not acquire a Schlieren image, which is noise free, due to the contamination. This makes it difficult to accurately detect the acoustic property.